Back spacing mechanism for typewriters or like machines



Dec. 27, 1955 w. H. KUPPER 2,728,437

BACK SPACING MECHANISM FOR TYPEWRITERS OR LIKE MACHINES Filed Aug. 20, 1953 I5 Sheets-Sheet l INVENTOR k wa 4+ ATTORNEY Dec. 27, 1955 w. H. KUPPER BACK SPACING MECHANISM FOR TYPEWRITERS 'OR LIKE MACHINES 5 Sheets-Sheet 2 Filed Aug. 20, 1953 rfla 8 PI. h m mmm m m. mm

ATTORNEYS Dec. 27, 1955 w. H. KUPPER BACK SPACING MECHANISM FOR TYPEWRITERS OR LIKE MACHINES 3 Sheets-Sheet 3 Filed Aug. 20, 1955 INVENTOR l//////CZ77Z H lfupper BY 4%OQZ United States Patent William H. Kupper, West Hartford, Conn., assignor to Royal McBee Corporation, a corporation of New York Application August 20, 1953, Serial No. 375,409

19 Claims. (Cl. 197-91) This invention relates to back spacing mechanism operating means for typewriting or like machines, and more particularly to means for operating back spacing mechanism by power supplied, e. g. by an electric motor.

An object of the invention is to provide a new and improved power operated back spacing mechanism, particularly adapted for performing repeated back spacing operations.

Another object of the invention is to provide mechanism of the kind referred to adapted selectively to cause either a single step back spacing operation or a succession of repeated back spacing step operations. A related object is to provide mechanism of this kind which may be controlled by a single key or the like, the arrangement being such that a quick depression followed by a substantially immediate releasing of the key will cause a single back spacing operation, and a depression of the key followed by holding the key down will cause repeated back spacing operations.

Another object of the invention is to provide mechanism of the kind referred to including a back spacing repeat operation determining means comprising a continuously running member such as a rotatable cam.

Another object of the invention is to provide a back spacing repeat operation determining cam mechanism including a follower which normally is so positioned as not to be engageable by the cam, in combination with means for eifecting a relative shifting between the cam and the follower so as to cause the latter to be disposed in the path of running of the cam.

A further object of the invention is to provide an improved resilient stop device for limiting the relative movement of two typewriter or the like parts.

Other objects of the invention will become apparent from a reading of the following description of a preferred embodiment of the invention, the appended claims, and the accompanying drawings, in which:

Figure 1 is a view, partly in elevation and partly in vertical section, for and aft of a typewriter embodying the invention, showing only some of the conventional or standard typewriter parts in order to illustrate the application of mechanism embodying the invention to a typewriter construction, the parts being shown in their normal or inactive positions;

Figure 2 is a detailed lower;

Figure 3 is a fragmentary view, partly in vertical section on the irregular line 3-3 of Figure 1 and partly in elevation, showing parts of an escapement mechanism and a back spacing mechanism in their normal or inactive positions;

Figure 4 is a fragmentary view, partly in vertical section and partly in elevation, showing the escapement and back spacing mechanisms illustrated in Figure 3, but with the parts in operated or active positions;

Figure 5 is a fragmentary horizontal sectional view showing repeat operation determining cam mechanism perspective view of a cam foland associated control means and connections, the parts all tions; I

Figure 6 is a fragmentary view, partly in elevation and partlyin section on the. line 6-6 of Figure 5, showing a pull link and toggle mechanism, the parts being shown in their normal positions and on an enlarged scale;

Figure 7 is a view similar to Figure 6, but showing the parts in their operated positions;

Figure 8 is a detailed perspective view of a bell crank forming part of mechanism for controlling a cam follower;

Figure 9 is a perspective view of a bracket for porting one end of a cam follower shaft;

Figure 10 is a view similar to Figure 6, but showing a toggle link equipped with a modified form of stop;

Figure 11 is a detailed perspective view of the stop shown in Figure 10; and

Figure 12 is a schematic or diagrammatic view showing operating connections for transmitting drive from an electric motor to a driving element, more particularly a snatch roll, and also to a repeat operation determining cam mechanism.

The invention may be embodied in typewriters or like machines of various kinds. For the purposes of illustration, the invention is shown as being embodied in an office type electric typewriter. The drawings show only enough of the standard or known typewriter construction to assist in illustrating the manner in which mechanism embodying the invention may be coordinated with other parts of a typewriter construction.

The known construction illustrated includes a main frame A on which a carriage B equipped with a platen C is mounted for letter spacing and return movements by means of a top rail 1 secured to the carriage, and rolling upon balls 2, which in turn are adapted to roll' on a frame-mounted bottom rail or track 3. e

, The carriage may be driven toward the left, that is, in the letter-spacing direction, by any suitable mechanism, for example, by a spring barrel 4 and draw band 5 of known or suitable construction.

For controlling the feeding of the carriage in letterspacing direction to take place by letter space increments, the carriage is equipped with a rack 6 cooperable with an escapement mechanism generally designated D. The rack 6 is carried by a bail 7 having arms 8-8 pivoted on the carriage at 9-9 and urged by springs 10 10 to rock counterclockwise as viewed in Figure 1 so as normally to hold the rack in engagement with an escapement pinion 11. The bail 7 and rack 6 may be swung upwardly by any suitable means (not shown) so as to disengage the rack 6 from the pinion 11 to enable the carriage to be shifted manually in the usual manner, The pinion 11 is coupled by a ratchet device (not shown) with an escapement wheel 12 journaled at 13 on an escapement frame or bracket 14.

The bracket 14 is equipped with cone-shaped bearing screws 15-15 extending into conformingly shaped bearing recesses in mounting ears 1616 integral with an oscillatable escapement rocker plate 17. The plate 17 is equipped with the usual fixed dog 18 and limber dog 19 pivoted on the plate as at 20, and urged counterclockwise as viewed in Figures 3 and 4 by a spring 21 interposed between a heel 22 on the limber dog and an motion transmitting some of the parts being shown in top plan, being shown in their normal or inactive posisup- , car 23 on the rocker plate 17. An abutment screw 24 has threaded connection with a boss or lug 25 on" the back of the plate 17, and can be adjusted for determining the limit of rocking of the limber dog 19 when the latter is engaged by a tooth of the escapement wheel 12. An escapement wheel check pawl 26 pivoted at 27 on the rocker plate 17, is urged counterclockwise by a spring 28 interposed between ears 29 and 30 on the pawl 26 and plate 17 respectively.

When the rocker plate 17 is oscillated back and forth,

the, dogs 18 and 19 will cooperatewith the escapement wheel 12 in awell known manner for effecting the desiredletter-spacing incremental movements of the car.- riage.

Withthe exception of power mechanism foroperating it, the back spacing mechanism may be of. known cpnstruction, and, as shown, is similar to the back spacing of the bell crank 33, is a rock arm '35, the upper end of which is pivoted to a thrust bar36, as. at 37. The bar 36 is bifurcated to provide upper and lower arms 36 and 36 The upper arm 36 is provided with a pin 38 which is received in a slot 39 formed in. a bracket 40 secured to the escapement bracket or frame 14, and

is formed with an upwardly extendingtooth 41 adapted to cooperate with the teeth on the rack 6 in amanner to be described later. The lower arm 36 of the bar 36 extends behind the bracket 40 as viewed in Figure 3, and the upper arm 36 extends in front of the bracket 40 so that the arms 36 and 36 being, disposed on OPT posite sides of the bracket 40, guide the thrust bar 36.

for reciprocation in the direction of carriage travel. For translating rocking of the bell crank 33 first into rocking and then into reciprocation of thethrust bar 36, the bell crank is formed with a heel '33 adapted to engage a projection 36? on the thrust bar 36. A spring 42 interposed between a pin 43 on the bar 36 and an arm 44 on the bracket 40 normally maintains the thrust bar 36 and rock arm in the positions shown in Figure 3.

An escapement wheel stop 45 is slotted to receive the pin 43 on the bar 36 and an adjustment locking screw 46, also carried by the bar 36, the arrangement being such that the stop '45 can be variably positioned longi-- tudinally with respect to the bar 36, and then locked in.

adjusted position.

A rack lock lever 47 is mounted-to rock on an adjust-v able pivot pin 48 carried by the bracket and is formed with an arcuate upper end part 4l overlying the front bar of the bail 7 but normally being maintained free of engagement with the bail bar by a spring'49'interposed between an car 50 on the rack lock 4;! and an ear 51 on the bracket 40.

Normally the parts are in the positions shown in Figure 3. During typing, the escapement mechanism D is operated in the usual manner toenable the escapement wheel 12 and pinion 11 to rotate step by step in the direction of the arrow a to effect incremental letterspacing movements of the carriage. In order to back space the carriage incrementally, the thrust link 31' is moved upwardly in a manner described hereinafter so as to rock the bell crank lever 33 and arm 35','and thereby move the thrust bar 36 toward the right as viewed in Figure 3. During the first part of the rightward movement of the thrust bar 36, the pin 38 will move away from the inclined left end of the slot 39 in the bracket 40 so that the bar 36 will be free to be moved upwardly by the spring 42 and by the turning moment imposed on the bar 36 by the heel 33 of the bell crank lever 33. In this way the tooth 41 on the bar 36 will:

be moved into a tooth interspace on the escapement rack 6. Also during the rightward movement of the bar 36,

engagement with the top of the bail 7, thereby locking the bail against upward movement. Atthe same time the escapement wheel stop willbe moved. into th 70 the right-hand end of the thrust bar lower arm 36 will; engage the rack lock 47 and swing it clockwise about its pivot so as to move its upper arcuate portion 47 into position shown in Figure 4 so as to prevent reverse rotation ofthe escapement wheel 12'. Continued movement of the thrust bar 36 toward the right, with its tooth 41 in engagement with the rack 6, will move the carriage one letter space toward the light, that is, in the contra letter spacing or return direction, as will be permitted by the ratchet coupling between the escapement wheel 12 and pinion 11. When the parts are returned from the positions shown in Figure 4 to the normal positions shown in Figure 3 by downward movement of the thrust link 31, the ratchet coupling between the escapernent wheel and pinion will hold the carriage in the back-spaced position to which itthas been moved.

Broadly considered, a single vertical reciprocation of the thrust link 31 and consequent single back spacing of the carriage are effected by power-driven means similar to power driven means disclosed in the patent to John F Klosk iand WilliamH. Kupper No. 2,577,467, dated December 4, 1951; The powerdriven means generally designatedE, is made effective by depression of a manually operableback spacing key F. Power is transmitted from the power-driven means-E; through attain of driving connections 6. The construction and arrangement of:

the 'parts in such that, upon depression of the back spat:-v ing key F, a quickly generated power impulseis, transmitted through a. cushion device embodied in the, train of connections G, tothe thrust link 31 so as to raise, the latter and operate the associated back spacing mechanism. in the manner previously described.

The power-driven mechanism E includes a drivingple; ment, which operates continuously, and controllabledriving connections, which normally are inoperative .orineffective, but which maybe conditioned by the operator to eifect operative driving connection between the continu-.

ouslymoving driving element or member and thetrain of connections G. The driver preferably is constitutedby a continuously v rotating element... more particularly a toothed snatch roll orbar 52, which may be of'knownv form, and whichisadapted to be driven in the direction of the arrow bin Figure l by any suitable means, but preferably by an electric motor M.

The means, for transmitting drive from the driver 52.

to. the connections G includes anactuator 53 which extendsv fore and aft of the typewriter and above the mem-. ber,5 2. The actuator 53 is pivoted asat 54..to. a lever 55,

at. a .point off-set relatively tothe pivotal mounting, 56.. of the lever on a fixed frame cross bar 57. The actuator has a forwardly .extending part 58 projecting under .an

abutmentor guide plate 59. mounted on the frameA, to;

extend parallel tothe snatch roll 52. A spring 60, interposed betweenv the front end of the-actuator 53 andan anchor plate 61, yieldably urges theactuator to rock clockwise, and thus normally maintains the actuator in the position shown in Figure, l with itsfront end part 58,

bearing against the, abutmentor guide plate 59. Another abutment 62. is, disposed below the abutment 59, andis slotted to receive andguide .thelower extremity ofthe, 3C".

tuator part 58 for sliding movements. The lever 55;-normally is heldin its inactive position, shown in Figure; 1, by a returning spring 63.,interposed' between an ear; 64 on the lever and an anchor plate 65 mountedon thefixed,

cross bar 57. by screws, one of which is shownat-66. The lever 55 has a stop projection 67 engageable witha fixed stop, strip ;68,for limiting the. returning movemeneof the lever vunder the urge of the spring 63.

In order to apply a power impulse to thetrain ,of-driving, connections G, the actuator 53 is operatively but indirectly connected to the driving member 52, the actuator itselfnever engaging the driving member. Mechanism for bringing about this-operative connection includes an interponent pawl element or part 69, pivoted as at,70 on the actuator. A -spring 71-, anchored to the actuator 53 and connected to 'thepawl 69, biasesor urgesthe latter to rock 'clockwiseso asto move itsdouble toothed nose- 69 *into engagement with the snatch roll'52: Normally, the pawl is maintained out of engagement with the snatch roll'by the restraining action of a control element or trigger 72 which is pivoted as at 73 on the actuator 53. In the normal position of the trigger, its rear end engages a holding surface 74 on the pawl so as to prevent the spring 71 from rocking the pawl 69 into drive-transmitting engagement with the driving member 52. The pawl part 69 is formed with an inclined resetter cam face 75 which is located just below the holding surface 74, and which is acted upon by the trigger for rocking the pawl counterclockwise, and thus resetting it in normal, inoperative position.

Operator controlled means for bringing about a single operative driving connection between the driver 52 and the actuator 53 includes the manually operable back spacing key F pivoted as at 76 on the frame A. The key F has an upward projection 77 disposed behind an arm 78 of an operating lever 79, pivoted as at 80 on a framemounted cross bar 81. The lever 79 has another arm 82 on which a limber dog or flipper 83 is pivoted at 84. A spring 85 urges the limber dog 83 to rock clockwise to yieldably retain it in its normal position of rest against a limit stop 86 on the lever arm 82. The dog 83 can swing counterclockwise from the position shown in Figure 1, but cannot move clockwise from this position. A returning spring 87, interposed between the key F and a short arm 88 on the lever 79, yieldably holds the lever 79 and the key F in their normal positions. When the parts are in their normal positions the spring 87 holds the lever 79 so that the lower end of the limber dog 83 overlies a contact car 89 on the actuator 53, and holds the key P so that a forward projection 90 on the key bears against a cushion stop 91.

In operation, when the back spacing key F is depressed, the lever 79 is rocked clockwise to cause the flipper 83 to push the actuator 53 downwardly to an initial extent sufficient to bring the trigger 72 into engagement with the abutment 62. This causes the trigger to be rocked clockwise about its pivot 73, so as to release the pawl part 69, which is then moved by the spring 71 into engagement with the snatch roll 52. The snatch roll then drives the pawl 69 and actuator 53 as a unit so as to rock the lever 55 and operate the back spacing mechanism through the train of connections G. When the pawl 69 is cast off from engagement with the snatch roll 52, the spring 60 lifts the actuator 53 to bring the trigger 72 into engagement with the upper, trigger-resetting abutment 59. This causes the trigger 72 to be rocked counterclockwise, so as to move its rear end against the resetting cam face 75 of the pawl 69, thereby restoring the latter to its inactive position. The parts of the mechanism E will then be returned to their normal positions by the spring 63 after the performance of a .single step back spacing operation.

Means are provided for adjusting or varying the amount of driving impulse generated by the powerrnechanism E. This variation or adjustment is effected by variably limiting the extent to which the teeth on the actuator pawl nose 69 enter tooth interspaces on the snatch roll 52 under the urge of the spring 71 when the restraint of the trigger 72 on the pawl 69 is discontinued. In the form shown, the actuator 53 is provided with a downwardly extending stop element or finger 92 which is disposed in front of and normally out of contact with a downwardly extending stop part, heel, or finger 93 on the pawl 69. When the pawl 69 is rocked clockwise by the spring 71 so as to move the teeth on the pawl nose 69 into snatch roll tooth interspaces, the pawl stop 93 moves toward the actuator stop 92, which may be so positioned as to be engaged by the stop 93 to arrest rocking of the pawl 69 before the pawl teeth move to the roots of the snatch roll tooth interspaces. By variably positioning one of the stops 92, 93, e. g., by bending the stop 92 towards or away from the stop 93, the extent to which the pawl teeth enter the tooth interspaces on the snatch roll can bevaried. Conse-' quently, the angle through which the snatch roll rotates while in contact with the pawl, which determines the amount of driving of the pawl 69 and actuator 53 by the snatch roll 52, can be varied. Any suitable means or construction may be provided for adjusting one of the stops 92, 93 relatively to the other, but in the preferred construction the stop 92 is formed integrally with the actuator 53 so as to be bendable toward or away from the stop 93.

In typewriters or like machines in which all or some of the instrumentalities to be operated, e. g., type bars, carriage return mechanism, tabulating mechanism, escapement mechanism as well as back spacing mechanism, are operated by power, it may be desirable to provide means for varying collectively the extent of driving of the several actuator pawls corresponding to the pawl 69 and associated with the other mechanism referred to. This may be accomplished by providing a knock-off bar 94 mounted on the main frame so as to extend under the front ends of all of the actuators corresponding to the actuator 53 shown in Figure 1. Any suitable means (not shown), may be provided for adjustably tilting or otherwise variably positioning the knock-01f bar 94 so that it will be engaged by the lower ends of the actuators to control the timing of disengagement of the associated actuator pawls from the snatch roll.

In general, the construction described so far does not, in itself, constitute the present invention. The invention resides in other parts to be described, and combinations of such other parts with each other and with parts already described.

In the construction shown as embodying the present invention in a preferred form, a pull link 95 is pivoted as at 96 to the lever 55 and is pivoted at 97 to a toggle device generally designated 98. The link 95 is constituted by two relatively slidable parts 95 -95 which are connected together for limited sliding movements by headed studs 99 fixed to the link part 95 and extending through respective slots 100 in the link part 95 A spring 101 interposed between an ear 102 on the link part 95 and an ear 103 on the link part 95 urges the two link parts to the relative positions shown in Figures 1 and 6, in which the parts may be considered as being contracted. When the power driven mechanism E is operated in the manner previously described to rock the lever 55 counterclockwise as viewed in Figure l, the link part 95* is pulled forwardly so as to transmit driving efiort through the spring 101 to the link part 95*, causing the latter also to be moved forwardly and to exert cushioned effort on the pivot 97 for operating the toggle device 98.

The toggle device 98 comprises an upper link element part 104 pivoted at 97 to the link part 95 and also pivoted at 97 to the top of a lower toggle link element 105, the bottom end of which is pivoted at 106 to a fixed frame part 107. The top of the upper toggle link 104 is pivoted at 108 to the lower end of the thrust link 31 previously referred to in connection with the description of the back spacing mechanism. The pivot 108 is guided for vertical movements in a slot 109 formed in a bracket 110 secured by screws 111 to the frame part 107.

The pivot structure 108 is designated only generally in Figures 1, 5, 6, 7 and 10, being illustrated in more detail in Figure 3. As shown in Figure 3, the pivot structure 108 includes a screw 112 which extends through a flanged sleeve 113, the latter extending through the lower end of the thrust link 31 and the upper end of the toggle link 104. The threaded end 114 of the screw 112 receives a nut 115 having a cylindrical guide part 115 extending through the slot 109 in the bracket 110 and bearing against a shoulder 116 on the screw 112. A spacer 117 is interposed between the bracket 110 and the upper toggle link 104. The arrangement is such that the structure 108 provides for relative pivotal movement between the lower end of the thrust link- 31 and the top 7 end of the upper toggle link 104, and also enables the thrust link 31 to be moved vertically.

Normally the returning spring 63 shown in Figure 1 holds the pull link 95 retracted or in the position shown in Figures 1 and 6, with the toggle links 194 and 1 55 in relatively collapsed or toggle-broken positions. The movement of the toggle link parts 164 and 105 to these positions, and the extent of retraction of the link 95 by the spring 63 is limited by engagement of a stop ear 116 on the lower toggle link 105 with a stop finger 119 on the upper toggle link 104.

In operation, when the mechanism E is activated to effect a single back spacing movement of the carriage, the link 95 is pulled forwardly so as to straighten the toggle mechanism 98 by moving its links 104 and 105 from the relative positions shown in Figure 6 to the relative positions shown in Figure 7. thereby raising the thrust link 31 and operating the back spacing mechanism. The straightening action of the toggle device 98 is lim ited by engagement of the stop ear 118 on the lower link 105 with a stop pad 120 on the upper toggle link 104. Engagement of the stop ear 118 with the stop pad 120, as shown in Figure 7, will not result in abruptly stopping the action of the power driven actuator 53 and the related parts, since the spring 101 can yield so as to permit a slight further forward movement of the link part 95 the lever 55, and the actuator 53.

Figure shows a modified toggle device construction in which the lower toggle link 105 is provided with a stop member 121 having a foot part 122 riveted at 123 to the link 105. The stop member 121 has a flexible arm part 124 extending from the foot 122 and being provided at its free end with a U-shaped contactor part 125 adapted to engage the stop finger 119 and the stop pad 120 on the upper toggle link 104. The stop member 121 preferably is formed of resilient sheet metal capable of yielding and providing a cushion when the contactor part 125 engages either the stop pad 120 when the links 104 and 195' are being straightened, i. e. unfolded, or the stop finger 119 when the links are being folded, that is when the toggle is broken.

In accordance with the invention, cyclically operable repeat operation determining means generally designated H is provided for causing the pawl part 69 of the power driven mechanism E repeatedly to engage the I snatch roll 52 so as to effect repeated operations of the mechanism E, the toggle device 98, the thrust member 31, and the back spacing mechanism, to effect as many step-by-step incremental movements as may be desired. Preferably, the repeat operation determining means H includes a cyclically operable member such as a continuously running lobed cam which is arranged to transmit motion through normally ineffective motion transmitting means generally designated I for causing the actuator pawl 69 to be moved into engagement with the snatch roll 52.

In the illustrative embodiment of the invention, the repeat operation dctermining means H includes a cam 126 having two lobes 127 and 128, and being mounted for rotation on a shaft 129 which may be journaled on the machine frame A in any suitable manner. Preferably, the cam 126 is arranged to be rotated continuously by the motor M which also operates the snatch roll 52. As shown in Figure 12, the motor M has a pulley 139 which drives a belt 131 trained around a pulley 132, fast with a pulley 133. A belt 134, passing around the pulley 133, is also trained around a pulley 135 fast on the cam shaft 129 for rotating the cam. Also fast with the cam shaft 129 is a pulley 136 which drives a belt 137 passing around a pulley 138 fast with the snatch roll 52. By this arrangement, the motor M drives both the cam 126 and the snatch roll 52, the relative diameters of the several pulleys being such that the earn 126 and snatch roll 52 rotate at such relative speeds as to provide for most efficient-operation.

The motion transmitting connections I include acam follower-lever 139js'ecnred toa' shaft 140. The shaft 140 is mounted for rocking movements by a bracket 141' secured to a frame part 142 by screws 111, and a bracket 143 secured to a frame part 144 by screws 145. The follower lever 139 is equipped with a follower roller 146 normally displaced laterally from the path of movement of the cam lobes 127 and 128, being maintained in such positionby a spring 147 interposed between the cam follower lever 139 and the bracket 143.

A wire link 148 is pivoted at 149 to the upper end of the follower lever 139, and is pivoted at 150 to an arm 151 secured to a shaft 152 journaled at one end in a fixed frame part 153, and journaled similarly or in any suitable. manner at its other end. Collars 154 and 155 secured to the shaft 152 on opposite sides of the frame part 153hold the shaft 152 against endwise movement. Also secured to the shaft 152 is an arm 156, the lower end of which is pivoted at 157 to a link 158 formed at its front end with a slot 159 which receives for sliding movements a pin 160 on the lower end of an arm 161 depending from the trigger 72.

In operation, when the cam follower lever 139 is shifted in a manner to be described later so as to place the follower roller 146 in the path of running of the cam lobes 127 and 128, successive engagement of the cam lobes with the roller 146 will cause the follower lever 139 repeatedly to be rocked forwardly and then returned by a spring 162 interposed between the follower lever 139 and a fixed anchor 163. Forward rocking of the follower lever 139 moves the link 148 so as to act through the lever 151 to rock the shaft 152 and the arm 156 clockwise as viewed in Figure 1, thereby causing the rear end of the slot 159 to bear against the pin 160 and rock the trigger '72 clockwise to release the pawl part 69 and enable it to be moved into engagement with the snatch roll 52. As previously explained, this will cause operation of the actuator 53, the pull link 95, the toggle device 98, and the thrust link 31 so as to effect a step movement of the back spacing mechanism. When the cam lobe which engaged the roller 146 moves beyond the roller, the spring 162 will return the follower lever 139 and its associated parts to their normal positions. By the time the roller 146 again is engaged by a cam lobe, the mechanism E and the parts connecting it to the back spacing mechanism will have been returned to normal positions, so that further engagement of a cam lobe with the follower roller 146 will cause the operations to be repeated.

If the trigger 72 is released in the manner previously described by pushing downwardly on the actuator 53 between periods of engagement of a cam lobe with the follower roller 146, the motion transmitting connections I will not interfere with movement of the trigger 72, because the lost motion device constituted by the slot 159 in the link 158 and the pin 160 on the depending trigger arm 161 will enable the trigger to be rocked even through the link 158 is not moved forwardly.

Manually manipulatable means including the key F previously referred to is provided for rendering the normally ineffective motion transmitting means I effective for transmitting motion from the repeat operation determining cam means H to the interponent pawl 69 for causing the latter to engage the snatch roll 52 and to be operated thereby. As shown in Figures 1 and 5, a pad 164 on the front end of the key lever extension 99 is disposed above and is adapted to engage an car 165 on a lever 166 pivoted at 167 on a bracket 168 secured to a stationary frame cross bar 169. A wire link 170 is pivoted at its front end at 171 to the lever 166 and has its rear end pivoted at 172 to an arm 173 of a bell crank lever 174 pivoted at 175 on the frame part 142. Another arm 176 of the bell crank lever 174 is formed with a round nose part 177 positioned adjacent a head 178 on the cam follower shaft 140.

In operation, whenthe key F is depressed the pad 164 5' is pressed downwardly on. the ear 165 to rock the lever 166 clockwise as viewed in Figure l, causing the link 170 to be pulled forwardly to rock the bell crank lever 174 clockwise as viewed in Figure 5, and thereby causing the round nose 177 on the bell crank 174 to press against the head 178 on the cam follower shaft 140 and move the latter and the follower arm 139 so as to place the follower roller 146 in the path of running of the cam 126. This will cause the cam follower roller 146 and lever 139 to be operated repeatedly by the cam lobes 127 and 128 as long as the key F is held depressed, thereby causing repeated engagements of the interponent pawl 69 with the snatch roll 52 and repeated operation of the back spacing thrust link 31 in the manner previously described.

Operation Normally the snatch roll 52 and cam 126 will be rotating continuously, and the other parts will be in the positions shown in Figure I. In order to effect a single incremental back spacing movement of the carriage B, the key F is depressed and then immediately released. This will rock the lever 79 and push the flipper 83 downwardly to depress the actuator 53 far enough to bring the front end of the trigger 72 into engagement with the abutment 62, thereby rocking the trigger and releasing the interponent pawl 69 so that it may be moved by the spring 71 into transient engagement with the snatch roll 52. Consequently, the actuator 53 and cushioned drive transmitting link device 95 will be driven forwardly to straighten the toggle links 104 and 105 and move the thrust link 31 upwardly to effect a single operation of the back spacing mechanism in the manner previously described.

When it is desired to effect a number of repeated incremental back spacing step movements of the'carriage B, the key F is depressed and held down for a period depending upon the number of back spacing step movements desired to be performed. Depression of the key F will rock the lever 166 and pull forwardly on the link 170 to rock the bell crank lever 174 and move the cam follower shaft 140 so as to place the follower roller 146 in the path of running of the cam 126. Each time the roller 146 is engaged by a cam lobe 127, 128, the follower lever 139 will be rocked so as to transmit motion through the link 148, arm 151, shaft 152, arm 156, and link 158 to the depending arm 161 on the trigger 72, thereby releasing the pawl 69 and enabling spring 71 into engagement with the snatch roll 52. This will cause the interponent 69 and actuator 53 to be moved forwardly so as to operate the back spacing thrust link 31 in the manner previously described, after which the pawl 69 will be cast oft from engagement with the snatch roll 52 and the parts will be returned to their normal positions by the springs 63 and 162. The cam follower roller 146 will be returned to its normal position while the next following cam lobe is approaching, and when this latter cam lobe moves into engagement with the roller 146 the operations will be repeated. Thus, for each cycle of operation of the cyclically operable repeat operation determining means H, there will be a step back spacing movement of the carriage B.

When it is desired to effect only a single back spacing movement of the carriage B, the operator is inclined to depress and then release the key F very quickly. It would be possible to depress and release the key F during the time when the follower roller 146 is in contact with a low part of the cam 126 and before the approaching lobe 127 or 128 engages the roller 146. Consequently, depression and quick releasing of the key F might not cause a back spacing operation of the carriage B under the influence of the repeat operation determining control cam 126. However, even a very quick depression and re leasing of the key F between cycles of operation of the cam 126, that is, between periods of engagement of the roller 146 with a cam lobe, must inevitably effect a single engagement of the pawl 69 with the snatch roll through it to be moved by the the intermediary of the single operation control means comprising the lever 79 and flipper 83, entirely independently of operation of the repeat operation determining means H. In effect, there are two control means, both operable by the key F, for causing respectively single step back spacing operation and repeat back spacing operation respectively. The control means comprising the lever 79 and flipper 83 effect single back spacing operation, whereas the control means comprising the lever 166, link and lever 174 govern the repeat back spacing operation.

The mechanism disclosed embodies the invention in a preferred form, but it is intended that the disclosure be illustrative rather than definitive. The invention is defined in the appended claims.

I claim:

1. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member;

an actuator; means connecting said actuator to said back 1 spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a continuously driven repeat operation determining means; normally ineffective motion transmitting means between said repeat operation determining means and said part; and control means adapted to be moved to operative position for rendering said motion transmitting means effective to cause repeated engagements of said part with said driving member and consequent repeated operation of said back spacing mechanism in response to operation of said repeat operation determining means as long as said control means is in operative position.

2. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a repeat operation determining means including a continuously driven cam; normally ineffective motion transmitting means between said cam and said part; and control means adapted to be moved to operative position for rendering'said motion transmitting means effective to cause repeated engagements of said part with said driving member and consequent repeated operation of said back spacing mechanism in response to operation of said cam as long as said control means is in operative position.

3. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a cyclically operable repeat operation determining means; normally ineffective motion transmitting means between said repeat operation determining means and said part; a repeat operation control means adapted to be moved to operative position for rendering said motion transmitting means.

effective to cause repeated engagements of said part with said driving member and consequent repeated operation of said back spacing mechanism in response to operation of said cyclically operable repeat operation determining means as long as said repeat operation controlsmeans is in operative position; and other control means capable of being operated between cycles of operation of said cyclically operable repeat operation determining means for effecting engagement of said part with said driving member prior to operation of said motion transmitting means in the next succeeding cycle of said cyclically operable repeat operation determining means.

4. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator tooperate said back spacing mechanism; a cyclically operable repeat operation determining means; normally inefiective motion transmitting means between said repeat operation determining means and said part; a repeat operation control means adapted to be moved to operative position for rendering said motion transmitting means effective to cause repeated engagements of said part with said driving member and consequent repeated operation of said back spacing mechanism in response to operation of said cyclically operable repeat operation determining means as long as said repeat operation control means is in operative position; other control means capable of being operated between cycles of operation of said cyclically operable repeat operation determining means for effecting engagement of said part with said driving member prior to operation of said motion transmitting means in the next succeeding cycle of said cyclically operable repeat operation determining means; and a single key operatively connected to both said repeat operation control means and said other control means.

5. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a repeat operation determining means including a continuously driven lobed cam; normally ineffective motion transmitting means between said repeat operation determining means and said part including a cam follower periodically engageable with said cam; a repeat operation control means adapted to be moved to operative position for rendering said motion transmitting means effective to cause repeated engagements of said part with said driving member and consequent repeated operation of said back spacing mechanism in response to operation of said lobed cam as long as said repeat operation control means is in operative position; and other control meanscapable of being operated between cycles of cam lobe engagement with said cam follower for effecting engagement of said part with said driving member independently of operation of said motion transmitting means by said repeat operation determining means.

6. in power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally dis engaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby. and for moving said actuator to-operate said back spacing mechanism; a repeat operation. determiningmeans inbyyandcontrol-means adaptedto be moved-to operative 12 cludinga continuously driven lobed-cam; normally ineffective, motion transmitting means between said repeat operationdetermining means and said part including a cam follower periodically engageable with said cam; a

1 repeat operation control'means adapted to be moved to operative position for rendering said motion transmitting means effective. to cause repeated engagements of said part with said driving member and consequent repeated operation of said-back spacing mechanism in response to operation of said lobed cam as long as said repeat operation control means is in operative position; other control means capable of being operated between cycles of cam lobe. engagement with said cam follower for efiecting engagement of said part with said driving member independently of operation of said motion transmitting means by said repeat=operation determining means; and a single key operatively connected to both said repeat operation control means and said other control means.

7. In power operated mechanism for a typewriter or likemachine, a carriage; a carriage back spacing mechanism for'moving said carriage in step-by-step increments inthe contra letter spacing direction; a driving member; an actuator; means including a cushioned drive transmitting device connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged fromsaid driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a continuously driven repeat operation determining means; normally inelfective motion transmitting means between said repeat operation determining means and said part; and control means adapted to be moved to operative position for rendering said motion transmitting means effective to cause repeated engagements ofsaid part with said driving member and consequent-repeated operation of said back spacing mechanism inresponse to operation of said repeat operation determining means as long as said control means is in operative position.

8. In power operated mechanism for a typewriter or iike machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means including a cushioned drive transmitting device connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a repeat operation determining means including a: continuously driven cam; normally ineffective motion transmitting means between said cam and said part; and control means adapted to be moved to operative position for rendering said motion transmitting means effectiveto cause repeated engagements of said part with said'driving member and consequent repeated operation of said backspacing mechanism in response to operation of'said cam aslong as said control means is in operative position.-

9. In power operated mechanism for a typewriter or like machine,- a-carriage; a carriage back spacing mechanism for moving Saidcarriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacingmechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a repeat operation determining means including a continuously running cam; motion transmitting means between said cam and said part including a cam follower'normally so positioned relatively to said cam as nottobe operable thereby but being adapted to be so positionedrelatively to; said cam as to-be operable thereposition for positioning said follower relatively to said cam so as to be operated thereby repeatedly to cause repeated engagements of said part with said driving member and consequent repeated operation of said back spacing mechanism in response to operation of said repeat operation determining means as long as said control means is in operative position.

10. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a repeat operation determining means including a continuously running cam; motion transmitting means between said cam and said part including a cam follower; means normally maintaining said cam follower out of the path of running of said cam; and control means connected to said cam follower and being movable to operative position for shifting said cam follower into the path of running of said cam, whereby said cam will eifect repeated operations of said cam follower and repeated engagements of said part with said driving member, and consequent repeated operations of said back spacing mechanism in response to continued running of said cam as long as said control means is in operative position.

ll. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a repeat operation determining means including a continuously running lobed cam; a cam follower periodically lobe-engageable therewith; motion transmitting means between said cam follower and said part; means normally maintaining said cam follower out of the path of running of said cam; repeat operation control means connected to said cam follower and being movable to operative position for shifting said cam follower into the path of running of said cam, whereby said cam will effect repeated operations of said cam follower and repeated engagements of said part with said driving member, and consequent repeated operations of said back spacing mechanism in response to continued running of said cam as long as said control means is in operative position; and other control means capable of being operated between periods of cam lobe engagement with said cam follower for effecting engagement of said part with said driving member independently of operation of said motion transmitting means by said repeat operation determining means.

12. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuator to said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a repeat operation determining means including a continuously running lobed cam; a cam follower periodically lobe-engageable therewith; motion transmitting means between said cam follower and said part; means normally maintaining said cam follower out of the path of running of said cam; repeat operation control means connected to said cam follower and being movable to operative position for shifting said cam follower into the path of running of said cam, whereby said cam will eflfect repeated operations of said cam follower and repeated engagements of said part with said driving member, and consequent repeated operations of said back spacing mechanism in response to continued running of said cam as long as said control means is in operative position; other control means capable of being operated between periods of cam lobe engagement with said cam follower for effecting engagement of said part with said driving member independently of operation of said motion transmitting means by said repeat operation determining means; and a single key operatively connected to both said repeat operation control means and said other control means.

13. In power operated mechanism for a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; a driving member; an actuator; means connecting said actuatorto said back spacing mechanism; a part on said actuator normally disengaged from said driving member but being adapted to be transiently engaged therewith to be moved thereby and for moving said actuator to operate said back spacing mechanism; a cyclically operable repeat operation determining means; normally ineffective means including a one way drive device for transmitting motion from said repeat operation determining means to said part; a repeat operation control means adapted to be moved to operative position for rendering said motion transmitting means effective to cause repeated engagements of said part with said driving member and consequent repeated operation of said back spacing mechanism in response to operation of said cyclically operable repeat operation determining means as long as said repeat operation control means is in operative position; and other control means capable of being operated between cycles of operation of said cyclically operable repeat operation determining means for effective engagement of said part with said driving member prior to operation of said motion transmitting means in the next succeeding cycle of said cyclically operable repeat operation determining means.

14. In a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; means for operating said back spacing mechanism including a toggle device comprising pivoted links; and a resilient stop on one of said links engageable with the other of said links when said links are relatively folded for limiting relative pivotal folding movement of said links.

15. In a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; means for operating said back spacing mechanism including a toggle device comprising pivoted links; and a spring metal stop blade fast with one of said links and being engageable with the other of said links when said links are relatively folded for limiting relative pivotal folding movement of said links.

16. In a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments in the contra letter spacing direction; means for operating said back spacing mechanism including a toggle device comprising pivoted links; and a spring metal stop member having a foot part attached to one of said links, a flexible arm part extending from said foot part, and a U-shaped contactor part at the free end of said flexible arm part engageable with the other of said links for limiting relative pivotal movement of said links.

17. In a typewriter or like machine, a member to be operated; an actuator; means for transmitting etfort from said actuator to said member to be operated including apair. of connected, relatively movable elements; and a spring metal stop member having a foot part attached to one of said elements, a flexible. arm part extending from said foot part, and a U-shaped contactor' part at the free end of said flexible arm part engageable with the other of said elements for limiting relativemovement of said elements.

18. In a typewriter or like machine, a carriage; a carriage back spacing mechanism for moving said carriage in step-by-step increments'in the contra letter spacing direction; power operated mechanism for effecting repeated operations of said back spacing mechanism including a lobed cam and a follower cyclically lobe engageable with said cam for being operated repeatedly by said cam to cause repeated operations of said back spacing mechanism; and single operation control means capable of being operated between cycles of lobe engagement of said follower with said cam for efiecting' a single operation of said backspacing mechanism independently of operation of-said follower.

19. In a typewriter or like machine, a carriage; a carriage back spacing mechanism folmoving said carriage in step-by-step increments: in the contra letter spacing direction; powerv operated mechanism for effecting repeated operations-10ft said back spacing mechanism including a lobed cam and a follower cyclically lobe engageable with said cam for beingoperated repeatedly by said cam to'cause repeated operations of saidback spacing mechanism; single operation control means capable of beingoperated' between cycles of lobe engagement of said follower with said cam for effecting a single operation'of said back spacing mechanism independently of operation of saidfollower; and a single key operable for causing operation of said power operated mechanism and for causing operation of said single operation control means.

References Cited in the file of this patent UNITED STATES PATENTS 1,883,697 Going Oct. 18, 1932 1,984,410 Hart Dec. 18, 1934 2,088,064 Koca July 27, 1937 2,577,467 Kloski et a1. Dec. 4, 1951 

